Semiconductor substrate having a serious effect of gettering heavy metal and method of manufacturing the same

ABSTRACT

A silicon dioxide layer overlies a monocrystal silicon substrate and has a first upper surface. A first monocrystal silicon layer overlies the first upper surface and has phosphorus atoms diffused. A second monocrystal silicon layer overlies the first monocrystal silicon layer. The first monocrystal silicon layer may have phosphorus or silicon atoms each of which has a positive electric charge instead of the phosphorus atoms diffused. A lattice mismatching layer may overlie the first upper surface instead of the first monocrystal silicon layer. The lattice mismatching layer has parts in each of which misfit dislocation is caused. The first and the second monocrystal silicon layers may overlie the monocrystal silicon substrate and layer, respectively. In this event, a silicon glass layer is interposed between the first and the second monocrystal silicon layers. The second monocrystal silicon layer has phosphorus atoms diffused.

This application is a division of application Ser. No. 08/160,352, filedNov. 29, 1993, pending.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a semiconductor substrate and a method ofmanufacturing the semiconductor substrate.

2. Description of the Related Art

In the manner which will be described more in detail, a conventionalsemiconductor substrate comprises a monocrystal silicon substrate, afirst silicon dioxide layer overlying on the monocrystal siliconsubstrate, a second silicon dioxide layer overlying the first silicondioxide layer, a gettering layer overlying the second silicon dioxidelayer, and a monocrystal silicon layer overlying the gettering layer.The conventional semiconductor substrate has an effect of getteringheavy metal that is not serious. Also, the conventional semiconductorsubstrate is expensive.

In the manner which will be described more in detail, anotherconventional semiconductor substrate comprises a monocrystal siliconsubstrate, a silicon dioxide layer overlying the monocrystal siliconsubstrate, a polycrystal silicon layer overlying the silicon dioxidelayer, and a monocrystal silicon layer overlying the polycrystal siliconlayer. This conventional semiconductor substrate has an effect ofgettering heavy metal that is not serious. Also, this other conventionalsemiconductor substrate is expensive.

In the manner which will be described more in detail, still anothersemiconductor substrate comprises a monocrystal silicon substrate, afirst silicon dioxide layer overlying the monocrystal silicon layer, asecond silicon dioxide layer overlying the first silicon dioxide layer,and a monocrystal silicon layer overlying the second silicon dioxidelayer. This semiconductor substrate has weak bonding strength betweenthe monocrystal silicon substrate and the monocrystal silicon layer.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide asemiconductor substrate which has an effect of gettering heavy metalthat is serious.

It is another object of this invention to provide a semiconductorsubstrate which is inexpensive.

It is still another object of this invention to provide a semiconductorsubstrate which has great bonding strength between a monocrystal siliconsubstrate and a monocrystal silicon layer.

Other objects of this invention will become clear as the descriptionproceeds.

According to an aspect of this invention, there is provided asemiconductor substrate which comprises a monocrystal silicon substratehaving a principal surface; a silicon dioxide layer overlying theprincipal surface and having a first upper surface; a first monocrystalsilicon layer overlying the first upper surface and having phosphorusatoms diffused in the first monocrystal silicon layer which has a secondupper surface; and a second monocrystal silicon layer overlying thesecond upper surface.

According to another aspect of this invention, there is provided asemiconductor substrate which comprises a monocrystal silicon substratehaving a principal surface; a silicon dioxide layer overlying theprincipal surface and having a first upper surface; a first monocrystalsilicon layer overlying the first upper surface and having phosphorusatoms each of which has a positive electric charge and is injected inthe first monocrystal silicon layer having a second upper surface; and asecond monocrystal silicon layer overlying the second upper surface.

According to still another aspect of this invention, there is provided asemiconductor substrate which comprises a monocrystal silicon substratehaving a principal surface; a silicon dioxide layer overlying theprincipal surface and having a first upper surface; a first monocrystalsilicon layer overlying the first upper surface and having silicon atomseach of which has a positive electric charge and is injected in thefirst monocrystal silicon layer having a second upper surface; and asecond monocrystal silicon layer overlying the second upper surface.

According to yet another aspect of this invention, there is provided asemiconductor substrate which comprises a monocrystal silicon substratehaving a principal surface; a silicon dioxide layer overlying theprincipal surface and having a first upper surface; a latticemismatching layer overlying the first upper surface and having a secondsurface and causing misfit dislocation to occur therein; and amonocrystal silicon layer overlying the second upper surface.

According to a different aspect of this invention, there is provided asemiconductor substrate comprising a monocrystal silicon substratehaving a principal surface; a first monocrystal silicon layer overlyingthe principal surface and having phosphorus atoms diffused in the firstmonocrystal silicon layer which has a first upper surface; a siliconglass layer overlying the first upper surface and having phosphorusatoms in the silicon glass layer which has a second upper surface; asecond monocrystal silicon layer overlying the second upper surface andhaving phosphorus atoms diffused in the second monocrystal silicon layerwhich has a third upper surface; and a third monocrystal silicon layeroverlying the third upper surface.

According to another different aspect of this invention, there isprovided a method which is for manufacturing a semiconductor substrateand which comprises the steps of: (A) preparing a monocrystal siliconsubstrate having a principal surface; (B) forming a silicon dioxidelayer on the principal surface so that the silicon dioxide layer has anupper surface; (C) preparing a monocrystal silicon film having a firstlower surface; (D) forming a second monocrystal silicon layer on thefirst lower surface so that the second monocrystal silicon layer hasphosphorus atoms diffused in the second monocrystal silicon layer and asecond lower surface; (E) bonding the silicon dioxide layer to thesecond monocrystal silicon layer with the upper surface placed adjacentto the second lower surface; and (F) grinding the monocrystal siliconfilm.

According to still another different aspect of this invention, there isprovided a method which is for manufacturing a semiconductor substrateand which comprises the steps of: (A) preparing a monocrystal siliconsubstrate having a principal surface; (B) forming a silicon dioxidelayer on the principal surface so that the silicon dioxide layer has anupper surface; (C) preparing a monocrystal silicon film having a firstlower surface; (D) forming a second monocrystal silicon layer on thefirst lower surface so that the second monocrystal silicon layer hasphosphorus atoms each of which has a positive electric charge and isinjected in the second monocrystal silicon layer having a second lowersurface; (E) bonding the silicon dioxide layer to the second monocrystalsilicon layer with the upper surface placed adjacent to the second lowersurface; and (F) grinding the monocrystal silicon film.

According to yet another different aspect of this invention, there isprovided a method which is for manufacturing a semiconductor substrateand which comprises the steps of: (A) preparing a monocrystal siliconsubstrate having a principal surface; (B) forming a silicon dioxidelayer on the principal surface so that the silicon dioxide layer has anupper surface; (C) preparing a monocrystal silicon film having a firstlower surface; (D) forming a second monocrystal silicon layer on thefirst lower surface so that the second monocrystal silicon layer hassilicon atoms each of which has a positive electric charge and isinjected in the second monocrystal silicon layer having a second lowersurface; (E) bonding the silicon dioxide layer to the second monocrystalsilicon layer with the upper surface placed adjacent to the second lowersurface; and (F) grinding the monocrystal silicon film.

According to a further different aspect of this invention, there isprovided a method which is for manufacturing a semiconductor substrateand which comprises steps of: (A) preparing a monocrystal siliconsubstrate having a principal surface; (B) forming a silicon dioxidelayer on the principal surface so that the silicon dioxide layer has anupper surface; (C) preparing a monocrystal silicon film having a firstlower surface; (D) forming a lattice mismatching layer on the firstlower surface so that the lattice mismatching layer has a second lowersurface and causes misfit dislocation therein; and (E) bonding thesilicon dioxide layer to the lattice mismatching layer with the uppersurface placed adjacent to the second lower surface; and (F) grindingthe monocrystal silicon film.

According to a yet further different aspect of this invention, there isprovided a method which is for manufacturing a semiconductor substrateand which comprises the steps of: (A) preparing a monocrystal siliconsubstrate having a principal surface; (B) preparing a monocrystalsilicon film having a first lower surface; (C) forming a silicon glasslayer on the first lower surface so that the silicon glass layer hasphosphorus atoms in the silicon glass layer which has a second lowersurface; (D) bonding the silicon glass layer to the monocrystal siliconsubstrate with the principal surface placed adjacent to the second lowersurface to diffuse the phosphorus atoms into the monocrystal siliconsubstrate and the silicon glass layer; and (F) grinding he monocrystalsilicon film.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic vertical sectional view of conventionalsemiconductor substrate;

FIG. 2 is a schematic vertical sectional view of another conventionalsemiconductor substrate;

FIG. 3 is a schematic vertical sectional view of still anotherconventional semiconductor substrate;

FIG. 4 is a schematic vertical sectional view of a semiconductorsubstrate according to a first embodiment of this invention;

FIG. 5 is a schematic vertical sectional view of a semiconductorsubstrate according to a second embodiment of this invention;

FIG. 6 is a schematic vertical sectional view of a semiconductorsubstrate according to a third embodiment of this invention;

FIG. 7 is a schematic vertical sectional view of a semiconductorsubstrate according to a fourth embodiment of this invention;

FIGS. 8 to 12 are schematic vertical sectional views of a semiconductorsubstrate at various steps of a method according to a fifth embodimentof this invention;

FIGS. 13 to 17 are schematic vertical sectional views of a semiconductorsubstrate at various steps of a method according to a sixth embodimentof this invention;

FIGS. 18 to 22 are schematic vertical sectional views of a semiconductorsubstrate at various steps of a method according to a seventh embodimentof this invention; and

FIGS. 23 to 26 are schematic vertical sectional views of a semiconductorsubstrate at various steps of a method according to an eighth embodimentof this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a conventional semiconductor substrate will firstbe described for a better understanding of this invention.

This conventional semiconductor substrate is disclosed in JapaneseUnexamined Patent Prepublication (Kokai) No. 37771/1990. In FIG. 1, thisconventional semiconductor substrate comprises a monocrystal siliconsubstrate 31 having a principal surface 33. A first silicon dioxidelayer 35 overlies the principal surface 33 and has a first upper surface37. A second silicon dioxide layer 39 overlies the first upper surface37 and has a second upper surface 41. A gettering layer 43 overlies thesecond upper surface 41 and has a third upper surface 45. A firstmonocrystal silicon layer 47 overlies the third upper surface 45.

The gettering layer 43 comprises a silicon dioxide film and particles ofoxygen deposited in the silicon dioxide film. As a result, thisconventional semiconductor substrate has an effect of gettering heavymetal that is not serious. Also, this conventional semiconductorsubstrate is expensive.

Referring to FIG. 2, another conventional semiconductor substrate willbe described for a better understanding of this invention. Similar partsare designated by like reference numerals.

This conventional semiconductor substrate is disclosed in JapaneseUnexamined Patent Prepublication (Kokai) No. 260468/1990. Thissemiconductor substrate comprises the monocrystal silicon substrate 31having the principal surface 33 and the first silicon dioxide layer 35having the first upper surface 37. A polycrystal silicon layer 49overlies the first upper surface 37 and has a fourth upper surface 51.The first monocrystal silicon layer 47 overlies the fourth upper surface51. This conventional semiconductor substrate is supplied with heatwhich is caused by forming the polycrystal silicon layer 49. As aresult, this conventional semiconductor substrate has an effect ofgettering heavy metal that is not serious. Also, this conventionalsemiconductor substrate is expensive.

Referring to FIG. 3, still another conventional semiconductor substratewill be described for a better understanding of this invention. Similarparts are designated by like reference numerals.

This conventional semiconductor substrate is disclosed in JapaneseUnexamined Patent Prepublication (Kokai) No. 54532/1990. Thisconventional semiconductor substrate comprises the monocrystal siliconsubstrate 31 having the principal surface 33, the first silicon dioxidelayer 35 having the first upper surface 37, and the second silicondioxide layer 39 having the second upper surface 41. The monocrystalsilicon layer 47 overlies the second upper surface 41. The secondsilicon dioxide layer 39 is formed in an ambient atmosphere whichcomprises oxygen and hydrogen chloride. As a result, this conventionalsemiconductor substrate has weak bonding strength between themonocrystal silicon substrate 31 and the first monocrystal silicon layer47.

Referring to FIG. 4, the description will proceed to a semiconductorsubstrate according to a first embodiment of this invention. Similarparts are designated by like reference numerals.

In FIG. 4, this semiconductor substrate comprises the monocrystalsilicon substrate 31 having the principal surface 33 and the firstsilicon dioxide layer 35 overlying the principal surface 33 and havingthe first upper surface 37. A second monocrystal silicon layer 53overlies the first upper surface 37 and has a fifth upper surface 55.The second monocrystal silicon layer 53 has phosphorus atoms diffused inthe second monocrystal silicon layer 53. The first monocrystal siliconlayer 47 overlies the fifth upper surface 55.

Referring to FIG. 5, the description will proceed to a semiconductorsubstrate according to a second embodiment of this invention. Similarparts are designated by like reference numerals.

In FIG. 5, this semiconductor substrate comprises the monocrystalsilicon substrate 31 having the principal surface 33 and the firstsilicon dioxide layer 35 overlying the principal surface 33 and havingthe first upper surface 37.

A third monocrystal silicon layer 57 overlies the first upper surface 37and has a sixth upper surface 59. The third monocrystal silicon layer 57has phosphorus or silicon atoms each of which has a positive electriccharge and is injected in the first monocrystal silicon layer 57. Thefirst monocrystal silicon layer 47 overlies the sixth upper surface 59.

Referring to FIG. 6, the description will proceed to a semiconductorsubstrate according to a third embodiment of this invention. Similarparts are designated by like reference numerals.

In FIG. 6, this semiconductor substrate comprises the monocrystalsilicon substrate 31 having the principal surface 33 and the firstsilicon dioxide layer 35 overlying the principal surface 33 and havingthe first upper surface 37. A lattice mismatching layer 61 of latticeconstants overlies the first upper surface 37 and has a seventh uppersurface 63. The lattice mismatching layer 61 causes misfit dislocationtherein. The first monocrystal silicon layer 47 overlies the seventhupper surface 63.

Referring to FIG. 7, the description will proceed to a semiconductorsubstrate according to a fourth embodiment of this invention. Similarparts are designated by like reference numerals.

In FIG. 7, this semiconductor substrate comprises the monocrystalsilicon layer 31 having the principal surface 33. A third monocrystalsilicon layer 65 overlies the principal surface 33. The thirdmonocrystal silicon layer 65 has phosphorus atoms diffused in the thirdmonocrystal silicon layer 65. The third monocrystal silicon layer 65 hasan eighth upper surface 67.

A silicon glass layer 69 overlies the eighth upper surface 67. Thesilicon glass layer 69 has phosphorus atoms in the silicon glass layer69. The silicon glass layer 69 has a ninth upper surface 71. A fourthmonocrystal silicon layer 73 overlies the ninth upper surface 71. Thefourth monocrystal silicon layer 73 has phosphorus atoms diffused in thefourth monocrystal silicon layer 73. The fourth monocrystal siliconlayer 73 has a tenth upper surface 75. The first monocrystal siliconlayer 47 overlies the tenth upper surface 75.

In FIGS. 4 to 7, the monocrystal silicon substrate 31 has a thickness of450 to 700 μm. The first silicon dioxide layer 35 has a thickness of0.05 to 2 μm. The first monocrystal layer 47 has a thickness of 0.05 to50 μm. The second monocrystal silicon layer 53 has a thickness of 0.05to 5 μm. The third monocrystal silicon layer 57 has a thickness of 0.05to 0.5 μm. The lattice mismatching layer 61 has a thickness of 0.05 to 5μm. The third monocrystal silicon layer 65 has a thickness of 0.05 to 5μm. The silicon glass layer 69 has a thickness of 0.05 to 2 μm. Thefourth monocrystal silicon layer 73 has a thickness of 0.05 to 5 μm.

Referring to FIGS. 8 to 12 together with FIG. 4, the description willproceed to a method of manufacturing the semiconductor substrateillustrated in FIG. 4.

In FIG. 8, the monocrystal silicon substrate 31 was prepared in theknown manner. In FIG. 9, the first silicon dioxide layer 35 was formedon the principal surface 33 by exposing, during one to three hours, themonocrystal silicon substrate 31 to an ambience which comprises H₂ andO₂ having a partial pressure ratio of H₂ :O₂ =1:1 to 2:1 and which isheld at a temperature of 1,000° to 1,200° C. The first silicon dioxidelayer 35 was formed to have the first upper surface 37.

In FIG. 10, the monocrystal silicon film 47' was prepared in the knownmanner. For example, the monocrystal silicon film 47' is formed by theCzochralski method and has boron atoms in the monocrystal silicon film47'. Also, the monocrystal silicon film 47' has a crystal azimuth of(100), an electrical resistivity of 10 to 50 Ω cm, and an initialconcentration of oxygen that is lower than 15×10¹⁷. The monocrystalsilicon film 47' has a thickness of 450 to 700 μm.

In FIG. 11, the second monocrystal silicon layer 53 was formed byinjecting phosphorus atoms in the monocrystal silicon film 47' toinclude phosphorus atoms having a dose amount which is greater than1×10¹⁵ atoms/cm² and by exposing, during one to three hours, themonocrystal silicon film 47 to an ambient atmosphere which is held at apressure around one atm. and at a temperature of 1,000° to 1,200° C. Thesecond monocrystal layer 53 was formed to have a first lower surface 77.

In FIG. 12, the second monocrystal layer 53 was bonded to the firstsilicon dioxide layer 35 with the first lower surface 77 placed adjacentto the first upper surface 37 by exposing, during one to three hours,the monocrystal silicon substrate 31, the first silicon dioxide layer35, the second monocrystal layer 53, and the monocrystal silicon film47' to an ambient atmosphere which is held at a pressure around one atm.and at a temperature of 1,000° to 1,200° C. In FIG. 4, the firstmonocrystal silicon layer 47 was formed by grinding the monocrystalsilicon film 47'. As a result, the semiconductor substrate was formed.

In FIG. 11, a silicon glass film having phosphorus atoms may be formedinstead of the second monocrystal silicon layer 53. The silicon glassfilm was formed by using a chemical vapor deposition method and byexposing, during one to three hours, the silicon glass film to anambient atmosphere which is held at a pressure around one atm. and at atemperature of 1,000° to 1,200° C.

Referring to FIGS. 13 to 17 together with FIG. 5, the description willproceed to a method of manufacturing the semiconductor substrateillustrated in FIG. 5.

The steps of FIGS. 13 to 15 are similar to the steps of FIGS. 8 to 10.

In FIG. 16, the third monocrystal silicon layer 57 was formed byinjecting the phosphorus or silicon atoms in the monocrystal siliconfilm 47'. Each of the phosphorus or silicon atoms has a positiveelectric charge. The third monocrystal silicon layer 57 was formed toinclude phosphorus or silicon atoms having a dose amount which isgreater than 1×10¹⁵ atoms/cm². The third monocrystal silicon layer 57was formed to have a second lower surface 79.

In FIG. 17, the third monocrystal silicon layer 57 was bonded to thefirst silicon dioxide layer 35 with the second lower surface 79 placedadjacent to the first upper surface 37 by exposing, during one to threehours, the monocrystal silicon substrate 31, the first silicon dioxidelayer 35, the third monocrystal silicon layer 57, and the monocrystalsilicon film 47' to an ambient atmosphere which is held at a pressurearound one atm. and at a temperature of 1,000° to 1,200° C. In FIG. 5,the first monocrystal layer 47 was formed by grinding the monocrystalsilicon film 47'. As a result, the semiconductor substrate was formed.

Referring to FIGS. 18 to 22 together with FIG. 6, the description willproceed to a method of manufacturing the semiconductor substrateillustrated in FIG. 6.

The steps of FIGS. 18 to 20 are similar to the steps of FIGS. 8 to 10.

In FIG. 21, the lattice mismatching layer 61 was formed on a third lowersurface 81 of the monocrystal silicon film 47' by using a chemical vapordeposition method so that the lattice mismatching layer 61 causes misfitdislocation therein. For example, this chemical vapor deposition methoduses an ambience which comprises SiH₂ Cl₂ and GeH₄ and which is held ata pressure of 10⁻³ to 10⁻⁴ Torr and at a temperature of 600° to 900° C.In this event, the lattice mismatching layer 61 is a layer whichcomprises SiGe. The lattice mismatching layer 61 was formed to have afourth lower surface 83.

In FIG. 22, the lattice mismatching layer 61 was bonded to the firstsilicon dioxide layer 35 with the fourth lower surface 83 placedadjacent to the first upper surface by exposing, during one to threehours, the monocrystal silicon substrate 31, the first silicon dioxidelayer 35, the lattice mismatching layer 61, and the monocrystal siliconfilm 47' to an ambient atmosphere which is held at a pressure around oneatm. and at a temperature of 1,000° to 1,200° C. In FIG. 6, the firstmonocrystal silicon layer 47 was formed by grinding the monocrystalsilicon film 47'. As a result, the semiconductor substrate was formed.

In FIG. 21, in case where the lattice mismatching layer 61 comprisesGaAs, the lattice mismatching layer 61 is formed by using a molecularbeam epitaxy method or a metal organic chemical vapor deposition method.In case where the lattice mismatching layer 61 comprises a materialexcept GaAs, the lattice mismatching layer 61 may be formed by thechemical vapor deposition method.

In FIGS. 11, 16, and 21, a bonding silicon dioxide layer (not shown) maybe formed on the first, the second, or the fourth lower surface 77, 79,or 83 in the manner illustrated in FIG. 9.

Referring to FIGS. 23 to 26 together with FIG. 7, the description willproceed to a method of manufacturing the semiconductor substrateillustrated in FIG. 7.

The steps of FIGS. 23 and 24 are similar to the steps of FIGS. 8 and 10.

In FIG. 25, the silicon glass layer 69 was formed on the third lowersurface 81 by using the chemical vapor deposition method so that thesilicon glass layer 69 has phosphorus atoms in the silicon glass layer69. For example, this chemical vapor deposition method uses an ambiencewhich comprises SiH₄, N₂, N₂, and PH₃ and which is held at a pressurearound 2 to 5 Torr during about 30 seconds to 2 minutes. In this event,the monocrystal silicon film 47' is held at a temperature around 400° C.The silicon glass layer 69 was formed to have a fifth lower surface 85.

In FIG. 26, the silicon glass layer 69 was bonded to the monocrystalsilicon substrate 31 with the fifth lower surface 85 placed adjacent tothe principal surface 33 by exposing, during 20 to 180 minutes, themonocrystal silicon substrate 31, the silicon glass layer 69, and themonocrystal silicon film 47' to an ambience which comprises O₂ and N₂and which is held at a pressure around one atm. and at a temperature of600° to 1,200° C. As a result, the third and the fourth monocrystalsilicon layers 65 and 73 (FIG. 7) was formed to have phosphorus atomswhich are diffused in the third and the fourth monocrystal siliconlayers 65 and 73 from the silicon glass layer 69.

In FIG. 7, the monocrystal silicon layer 47 was formed by grinding themonocrystal silicon film 47'. As a result, the semiconductor substratewas formed.

In FIG. 1, a diode (not shown) was formed by diffusing phosphorus atomsin the monocrystal silicon layer 47 having a surface area of 1 mm². Whenthis diode is supplied with an inverse bias voltage of 5 V, a leakcurrent of around 10⁻¹⁰ A/cm² flows in this diode.

In FIG. 4, a diode (not shown) was formed by diffusing phosphorus atomsin the monocrystal silicon layer 47 having a surface area of 1 mm². Whenthis diode is supplied with an inverse bias voltage of 5 V, a leakcurrent of around 10⁻¹¹ to 10⁻¹² A/cm² flows in this diode.

Although the invention has been described in detail above in connectionwith various preferred embodiments thereof, it will be appreciated bythose skilled in the art that these embodiments have been providedsolely for purposes of illustration, and are in no way to be consideredas limiting the invention. Instead, various modifications andsubstitutions of equivalent techniques will be readily apparent to thoseskilled in the art upon reading this specification, and suchmodifications and substitutions are to be considered as falling withinthe true scope and spirit of the following claims.

What is claimed is:
 1. A method of manufacturing a semiconductorsubstrate, comprising the steps of:preparing a monocrystal siliconsubstrate having a principal surface; forming a silicon dioxide layer onsaid principal surface so that said silicon dioxide layer has an uppersurface; preparing a monocrystal silicon film having a first lowersurface; forming a monocrystal silicon layer on said first lower surfaceso that said monocrystal silicon layer has phosphorus atoms diffused insaid monocrystal silicon layer and a second lower surface; bonding saidsilicon dioxide layer to said monocrystal silicon layer with said uppersurface placed adjacent to said second lower surface; and grinding saidmonocrystal silicon film, leaving a portion of said monocrystal siliconfilm and all of said monocrystal silicon layer on said substrate,whereby said portion of said monocrystal silicon film and saidmonocrystal silicon layer on said substrate are for Bettering heavymetal.
 2. A method of manufacturing a semiconductor substrate,comprising the steps of:preparing a monocrystal silicon substrate havinga principal surface; forming a silicon dioxide layer on said principalsurface so that said silicon dioxide layer has an upper surface;preparing a monocrystal silicon film having a first lower surface;forming a monocrystal silicon layer on said first lower surface so thatsaid monocrystal silicon layer has phosphorus atoms each of which has apositive electric charge and is injected in said monocrystal siliconlayer having a second lower surface; bonding said silicon dioxide layerto said monocrystal silicon layer with said upper surface placedadjacent to said second lower surface; and grinding said monocrystalsilicon film, leaving a portion of said monocrystal silicon film and allof said monocrystal silicon layer on said substrate, whereby saidportion of said monocrystal silicon film and said monocrystal siliconlayer on said substrate are for gettering heavy metal.
 3. A method ofmanufacturing a semiconductor substrate, comprising the stepsof:preparing a monocrystal silicon substrate having a principal surface;forming a silicon dioxide layer on said principal surface so that saidsilicon dioxide layer has an upper surface; preparing a monocrystalsilicon film having a first lower surface; forming a second monocrystalsilicon layer on said first lower surface so that said secondmonocrystal silicon layer has silicon atoms each of which has a positiveelectric charge and is injected in said second monocrystal silicon layerhaving a second lower surface; bonding said silicon dioxide layer tosaid second monocrystal silicon layer with said upper surface placedadjacent to said second lower surface; and grinding said monocrystalsilicon film.
 4. A method of manufacturing a semiconductor substrate,comprising the steps of:preparing a monocrystal silicon substrate havinga principal surface; preparing a monocrystal silicon film having a firstlower surface; forming a silicon glass layer on said first lower surfaceso that said silicon glass layer has phosphorus atoms in said siliconglass layer and has a second lower surface; bonding said silicon glasslayer to said monocrystal silicon substrate with said principal surfaceplaced adjacent to said second lower surface to diffuse said phosphorusatoms into said monocrystal silicon substrate and said silicon glasslayer; and grinding said monocrystal silicon film, leaving a portion ofsaid monocrystal silicon film and all of said silicon glass layer onsaid substrate, whereby said portion of said monocrystal silicon filmand said silicon glass layer on said substrate are for gettering heavymetal.
 5. The method of claim 1, wherein said monocrystal silicon filmhas a thickness of 450 to 700 micrometers before grinding and athickness of 0.05 to 50 micrometers after grinding.
 6. The method ofclaim 5, wherein said monocrystal silicon layer has a thickness of 0.05to 5 micrometers.
 7. The method of claim 2, wherein said monocrystalsilicon film has a thickness of 450 to 700 micrometers before grindingand a thickness of 0.05 to 50 micrometers after grinding.
 8. The methodof claim 2, wherein said monocrystal silicon layer has a thickness of0.05 to 5 micrometers.
 9. The method of claim 3, wherein the step ofgrinding said monocrystal silicon film comprises the step of leaving aportion of said monocrystal silicon film and all of said monocrystalsilicon layer on said substrate, whereby said portion of saidmonocrystal silicon film and said monocrystal silicon layer on saidsubstrate are for gettering heavy metal.
 10. The method of claim 9,wherein said monocrystal silicon film has a thickness of 450 to 700micrometers before grinding and a thickness of 0.05 to 50 micrometersafter grinding.
 11. The method of claim 9, wherein said monocrystalsilicon layer has a thickness of 0.05 to 5 micrometers.
 12. The methodof claim 4, wherein said monocrystal silicon film has a thickness of 450to 700 micrometers before grinding and a thickness of 0.05 to 50micrometers after grinding.
 13. The method of claim 4, wherein saidmonocrystal silicon layer has a thickness of 0.05 to 2 micrometers.